package com.atguigu.juc.interview.lock;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 *
 *
 *      多个线程同时读一个资源类没有任何问题 ，所以为了满足并发量，读取共享资源应该可以同时进行
 *      但是如果有一个线程想去写共享资源，就不应该再有其他线程可以对资源进行读或写
 *      总结:
 *           读-读共享
 *           读-写不能共存
 *           写-写不能共存
 * @author leimingchao
 * @create 2021-04-21 17:39
 */
class MyCache{
    private volatile Map<String,Object> map=new HashMap<>();
    private ReadWriteLock readWriteLock=new ReentrantReadWriteLock();

    public void put(String key,Object value){
        readWriteLock.writeLock().lock();
        try {
           System.out.println(Thread.currentThread().getName()+"\t 写入数据"+key);
           try {
               TimeUnit.MILLISECONDS.sleep(300);
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           map.put(key,value);
           System.out.println(Thread.currentThread().getName()+"\t 写入完成" +key);
        }finally {
           readWriteLock.writeLock().unlock();
        }
    }

    public void get(String key){
       readWriteLock.readLock().lock();
       try {
           System.out.println(Thread.currentThread().getName()+"\t 读取数据------------"+key);
           try {
               TimeUnit.MILLISECONDS.sleep(300);
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           Object value = map.get(key);
           System.out.println(Thread.currentThread().getName()+"\t 读取完成-------------");
       }finally {
           readWriteLock.readLock().unlock();
       }
    }
}


public class ReadWriteLockDemo {
    public static void main(String[] args) {
        MyCache myCache=new MyCache();
        for (int i=1;i<=5;i++){
            final int tempInt=i;
            new Thread(()->{
                myCache.put(tempInt+"",tempInt+"");
            },String.valueOf(i)).start();
        }

        for (int i=1;i<=5;i++){
            final int tempInt=i;
            new Thread(()->{
                myCache.get(tempInt+"");
            },String.valueOf(i)).start();
        }
    }
}
